Change where your enter key or talk key is bound on the alts. Not sure if you can do it with your setup, but the easiest way I can think of is have enter to only talk with your main, and shift+enter to talk with everyone. You should be able to bind talk with your alts to F12 or something that you don't use which just requires an extra key press when you want to emote with everyone.

This is why I love AHK.